// Copyright (c) AlphaSierraPapa for the SharpDevelop Team (for details please see \doc\copyright.txt)
// This code is distributed under the GNU LGPL (for details please see \doc\license.txt)
using System;
using System.Collections.Generic;
namespace ICSharpCode.AvalonEdit.Rendering
{
/// <summary>
/// Base class for <see cref="IVisualLineTransformer"/> that helps
/// splitting visual elements so that colors (and other text properties) can be easily assigned
/// to individual words/characters.
/// </summary>
public abstract class ColorizingTransformer : IVisualLineTransformer, ITextViewConnect
{
/// <summary>
/// Gets the list of elements currently being transformed.
/// </summary>
protected IList<VisualLineElement> CurrentElements { get; private set; }
/// <summary>
/// <see cref="IVisualLineTransformer.Transform"/> implementation.
/// Sets <see cref="CurrentElements"/> and calls <see cref="Colorize"/>.
/// </summary>
public void Transform(ITextRunConstructionContext context, IList<VisualLineElement> elements)
{
if (elements == null)
throw new ArgumentNullException("elements");
if (this.CurrentElements != null)
throw new InvalidOperationException("Recursive Transform() call");
this.CurrentElements = elements;
try {
Colorize(context);
} finally {
this.CurrentElements = null;
}
}
/// <summary>
/// Performs the colorization.
/// </summary>
protected abstract void Colorize(ITextRunConstructionContext context);
/// <summary>
/// Changes visual element properties.
/// This method accesses <see cref="CurrentElements"/>, so it must be called only during
/// a <see cref="Transform"/> call.
/// This method splits <see cref="VisualLineElement"/>s as necessary to ensure that the region
/// can be colored by setting the <see cref="VisualLineElement.TextRunProperties"/> of whole elements,
/// and then calls the <paramref name="action"/> on all elements in the region.
/// </summary>
/// <param name="visualStartColumn">Start visual column of the region to change</param>
/// <param name="visualEndColumn">End visual column of the region to change</param>
/// <param name="action">Action that changes an individual <see cref="VisualLineElement"/>.</param>
protected void ChangeVisualElements(int visualStartColumn, int visualEndColumn, Action<VisualLineElement> action)
{
if (action == null)
throw new ArgumentNullException("action");
for (int i = 0; i < CurrentElements.Count; i++) {
VisualLineElement e = CurrentElements[i];
if (e.VisualColumn > visualEndColumn)
break;
if (e.VisualColumn < visualStartColumn &&
e.VisualColumn + e.VisualLength > visualStartColumn)
{
if (e.CanSplit) {
e.Split(visualStartColumn, CurrentElements, i--);
continue;
}
}
if (e.VisualColumn >= visualStartColumn && e.VisualColumn < visualEndColumn) {
if (e.VisualColumn + e.VisualLength > visualEndColumn) {
if (e.CanSplit) {
e.Split(visualEndColumn, CurrentElements, i--);
continue;
}
} else {
action(e);
}
}
}
}
/// <summary>
/// Called when added to a text view.
/// </summary>
protected virtual void OnAddToTextView(TextView textView)
{
}
/// <summary>
/// Called when removed from a text view.
/// </summary>
protected virtual void OnRemoveFromTextView(TextView textView)
{
}
void ITextViewConnect.AddToTextView(TextView textView)
{
OnAddToTextView(textView);
}
void ITextViewConnect.RemoveFromTextView(TextView textView)
{
OnRemoveFromTextView(textView);
}
}
}